100% CPU after 4.1.1 upgrade from 4.0.20

Please do "lsof -n -p <pid_of_100%_CPU_process>", we need to find out what is file handle 7.
Please also do "kill -USR2 <pid_of_100%_CPU_process>", it turns on debug logging to help us identify the problem. Server level configuration, "Log Level" should be "DEBUG", "Debug Level" is "NONE".